Want to make 3D wall art how to project/bake texture from image plane to the walls of a room?
As Rob says, you should use the Project From View mode when you unwrap.


Import your image in the the UV Editor. Move your camera in front of your box until you get the view you want. In Edit mode make sure your box is subdivided enough, otherwise the projection will bug. Press U > Project From View.





Move or scale your UV as you want in the UV Editor. Create your material, load the image in the Image Texture node.





If you stay in the camera view you'll see your image as it is, i.e. it will appear flat. If you move your view you'll see how the image has been projected on the surfaces.